<!DOCTYPE html>
<html>
  <style>
    body {
      margin: 0px;
    }
    #spacer {
      height: 120vh;
      width: 120vw;
      border: solid 1px black;
    }
    #scroller {
      height: 200px;
      width: 200px;
      overflow: scroll;
      border: solid 1px red;
    }
    #inner-spacer {
      height: 400px;
      width: 400px;
      border: solid 1px black;
    }
  </style>
  <body>
    <div id="scroller" tabindex=0>
      <div id="inner-spacer"></div>
    </div>
    <div id="spacer"></div>
  </body>
</html>
